Silent chain in which strength and elongation of link row are uniformized

ABSTRACT

A silent chain with strength and elongation of respective link rows made uniform, elongation of every link made equal regardless of elastic and/or plastic deformation, and inexpensive production cost, is provided. The silent chain includes a first link row, a second link row, a connection pin and a pin stopper. Each of the first and second link row consists of a guide plate and a same number of link plates whose shapes and sizes are the same to configure the equal adjacent link rows. The first and second link rows are arranged in a stagger state in the chain longitudinal direction and connected alternately with the connection pins. The guide plates and the link plates of the first and second link row are composed relatively rotatable to the connection pins. A plurality of the first and second link rows are alternately arranged in mirror image symmetry.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a silent chain wound to a pairof sprockets that are apart from each other to transmit power from adrive sprocket to a follower sprocket.

[0003] 2. Prior Art

[0004] The silent chain is a chain wound to a pair of sprockets that areapart from each other to transmit power from the drive sprocket to thefollower sprocket. For example, the silent chain disclosed in JapanesePatent No. 3035206 is one in which a link row that consists of a pair ofguide plates and N pieces of link plates and a link row that consists ofN+1 pieces of link plates are alternately arranged, which are formedendlessly by connection pins.

[0005] In the silent chain described in the foregoing gazette, the linkplates in the link row including the guide plate are thin and the linkplates in the link row that does not include the guide plate arepartially thick, from a viewpoint of considering balance of tensilestrength in each link row.

[0006] A first problem is that strength is different between the linkrow including the guide plate and the link row that does not include theguide plate.

[0007] The link row including the guide plate has the guide plates inaddition to the link plates. The guide plate also bears a load appliedto the silent chain. The link row that does not include the guide platebears the load applied to the silent chain only by the link plates. Forthis reason, it is extremely difficult to uniformize the strength ofeach link row.

[0008] A second problem is that a pitch becomes easily different betweenthe link row including the guide plate and the link row that does notinclude the guide plate.

[0009] If the silent chain does not adopt the invention described in theforegoing gazette but all link plates are the same, the strength of thelink row including the guide plate increases, and elongation of the linkrow including the guide plate becomes smaller comparing to elongation ofthe link row that does not include the guide plate.

[0010] Since load balance is taken in consideration in the silent chainthat adopts the invention described in the foregoing gazette, elongationof each link row becomes closer to a certain extent. However, elongationof the link row is caused by: (1) flexure of pin; (2) load and stressapplied to the link plate; (3) load and stress applied to the guideplate; (4) deformation of the guide plate; (5) plastic deformationbetween pin and pin hole when a proof load is applied; or the like.Therefore, if a configuration of the link row is different, the pitchitself becomes easily different and change of pitch is also differentwhen a load is applied.

[0011] If the pitch and its change are different in each link row,conditions for engagement with the sprocket are also different in eachlink row. When the conditions for engagement are different in each linkrow, a problem such as engagement failure and noise occurs. Such aproblem causes adverse effect to the life of entire silent chain.

[0012] A third problem is that two or more kinds of link plates must becontrolled and assembled correctly.

[0013] The length, the height and the thickness of a small link plateare approximately 12 mm, approximately 7 mm and approximately 1 mmrespectively. A thickness difference of link plates which have differentthickness is approximately 0.4 mm. It is extremely difficult torecognize the thickness difference only by eyesight on-site of massproduction. Accordingly, although part control is performed accuratelywith another method to prevent mixture of a different link plate, thecontrol is not easy. Further, since different link plates are assembledin a link, assembly is laborious and quite non-economical.

SUMMARY OF THE INVENTION

[0014] The object of the present invention is to provide a silent chainin which configurations of link rows are uniformized to make thestrength of the link rows equal.

[0015] Another object of the present invention is to provide a silentchain in which elongation of each link is made equal regardless ofelastic deformation and/or plastic deformation.

[0016] Still another object of the present invention is to provide asilent chain in which the number of parts is reduced to reduce aproduction cost.

[0017] The present invention has solved the foregoing problems by thefollowing silent chain. A silent chain that includes:

[0018] a first link row that consists of one guide plate and N pieces oflink plates;

[0019] a second link row that consists of one guide plate and N piecesof link plates; and

[0020] a connection pin, in which

[0021] the guide plates of the first link row and the second link roware in the same shape and size, the link plates of the first link rowand the second link row are in the same shape and size, the first linkrow and the second link row are arranged in a stagger state in a chainlongitudinal direction and connected alternately with the connectionpin, and the guide plates and the link plates of the first link row andthe second link row are composed relatively rotatable to the connectionpins.

[0022] In the silent chain of the present invention composed asdescribed above, a guide plate is arranged over to an outermost linkplate of an adjacent second link row at one side of the first link row,and the guide plate is not provided at the other side of the first linkrow. On the contrary, a guide plate is arranged over to an outermostlink plate of an adjacent first link row at the other side of the secondlink row, and the guide plate is not provided at one side of the secondlink row. Therefore, only one guide plate exists at each link row andthe guide plates are arranged in a stagger state in a longitudinaldirection of chain.

[0023] The configuration of each link row is the same. Specifically,each link row consists of the guide plate of the same number and thesame shape and size and the link plates of the same number and the sameshape and size. Then, the guide plate and the link plates of each linkrow are composed relatively rotatable to the connection pin.

[0024] Accordingly, since the load applied to each link row is the same,the load and the stress applied to the guide plates of the first linkrow and the guide plates of the second link row are the same. Further,the load and the stress applied to the link plate closest to the guideplate of the first link row and the link plate closest to the guideplate of the second link row are the same. Moreover, the first andsecond link rows have the same load and stress applied to the linkplates. The first and second link rows have the same strength bycomposing the link row as described above.

[0025] As in the foregoing, since the load and the stress applied toeach guide plate and link plate are the same, the elongation of theguide plate and the link plate is also the same regardless of theelastic deformation and/or the plastic deformation. The same elongationin the first and second rows causes the same pitch and its change ineach link row.

[0026] In other words, the strength and the elongation of each link roware uniformized in the silent chain of the present invention.Accordingly, all the link rows are engaged with the sprocket on the sameconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a principal-portion plan view of an embodiment of asilent chain according to the present invention.

[0028]FIG. 2 is a front view of FIG. 1.

PREFERRED EMBODIMENTS OF THE INVENTION

[0029] The embodiment of the silent chain according to the presentinvention will be described with reference to the drawings. Typicalpurposes of the silent chain are an engine for automobile, atransmission for an automobile and a transfer for an automobile. In suchpurposes, the silent chain is endlessly wound to a pair of sprocketsthat are apart from each other, and transmits power from the drivesprocket to the follower sprocket.

[0030]FIG. 1 is the principal-portion plan view of an embodiment of asilent chain 10 according to the present invention, and FIG. 2 is thefront view of FIG. 2. The silent chain 10 basically includes: a firstlink row 20; a second link row 30; a connection pin 12; and a pinstopper 14.

[0031] The first link row 20 consists of a guide plate 22 and three linkplates 24. Each link plate 24 has the same shape and size. The secondlink row 30 consists of a guide plate 32 and three link plates 34. Eachlink plate 34 has the same shape and size.

[0032] Furthermore, the guide plate 22 of the first link row 20 and theguide plate 32 of the second link row 30 have the same shape and size,and the link plate 24 of the first link row 20 and the link plate 34 ofthe second link row 30 also have the same shape and size.

[0033] In the silent chain 10 of this embodiment, the first link row 20and the second link row 30 are arranged alternately in a stagger state.The guide plates (22, 32) are positioned on an outermost side, the firstlink row 20 and the second link row 30 are assembled in a comb-teethstate, the connection pin 12 of a cylindrical shape is inserted intocommon pin holes, and the silent chain 10 is thus formed.

[0034] With this configuration, the strength and the elongation of thelink rows (20, 30) are uniformized. Each of the link rows (20, 30) hasthe same configuration of the guide plate and link plate. Since the loadapplied to each link row is the same, the same load and the stress areapplied to the guide plate and the link plate. Accordingly, differenceof the strength and the elongation of each link row is eliminated.

[0035] From a viewpoint of uniformizing the strength and the elongationof each link row, it is preferable to make the relation between theguide plate (22, 32) and the link plates (24, 34) of each link row (20,30) and the connection pin 12 equal. In this embodiment, each of guideplates (22, 32) includes a pair (front and rear) of pin holes (26, 36).The inner diameter of the pin holes (26, 36) is larger than the outerdiameter of the connection pin 12. Further, each of the link plates (24,34) also includes a pair (front and rear) pin holes (28, 38). The innerdiameter of the pin holes (28, 38) is larger than the outer diameter ofthe connection pin 12.

[0036] Accordingly, the guide plate (22, 32) and the link plates (24,34) of each link row (20, 30) are relatively rotatable to the connectionpin 12. When the connection pin 12 is fitted into the guide plate andthe link plates of one link row, sliding movement occurs between theguide plate and the link plates of another link row and the connectionpin 12. The guide plate and the link plates of any link row (20, 30) arecomposed so as to be rotatable in sliding movement with the connectionpin 12, and thus the relation between the first link row 20 and theconnection pin 12 and the relation between the second link row 30 andthe connection pin 12 can be made equal. Accordingly, elongation of onlyone link row caused by abrasion or the like does not occur. Even ifelongation occurs, the first link row 20 and the second link row 30 havethe same elongation.

[0037] Further, the guide plate (22, 32) and the link plates (24, 34) ofeach link row (20, 30) freely rotate and slide to the connection pin 12of a cylindrical shape, abrasion of the connection pin 12 disperses toall periphery of the pin without occurring in a particular region.Accordingly, the silent chain 10 of this embodiment has improvedelongation endurance.

[0038] Then, the guide plate (22, 32) and the link plates (24, 34) ofany link row (20, 30) are composed so as to be rotatable in slidingmovement with the connection pin 12, it is necessary that the connectionpin 12 is bound to a predetermined region. In this embodiment, fasteningmeans such as fitting, snap-fit and riveting fastens the pin stoppers 14of a ring shape at both ends of the connection pin 12 outside the guideplates (22, 32).

[0039] As described, in the silent chain according to the presentinvention, the number and shape of the guide plate and the link plateare the same for each link row, and the guide plates and the link platesof each link row are composed relatively rotatable to the connectionpin. The strength and the elongation of each link row are uniformizedwhen the link row is composed in this manner.

[0040] Conventionally, although there has existed a problem that a linkrow that does not include the guide plate is easily fractured, enduranceimproves to fracture when a link row without a difference of strengthand elongation is adopted, and a life lengthens on this viewpoint.

[0041] Since the strength of the link row is uniformized and the linkrow thus does not have a difference of strength and elongation, thepitch and its change of each link row are also uniformized. In the statebefore the proof load is applied immediately after manufacturing thesilent chain, the pitch is usually finished in the same dimension. Evenif the proof load is applied to this state and even if a tensile load isfurther applied at a using time, the plastic deformation due to theproof load and the elastic deformation due to the tensile load in ausing time are the same with each link row since the configuration ofthe link rows is substantially the same. Uniformizing the pitch and itschange in each link row makes engagement conditions with the sprocketequal with each link row, the life lengthens on this viewpoint as well.

[0042] In the present invention, only one kind of link plate is requiredto form the silent chain in which the strength and the elongation areuniformized. Accordingly, the number of parts, the number of partcontrol processes and the number of assembly processes are reduced tomanufacture the silent chain economically.

[0043] Further, since two or more kinds of link plates are not usedwhere a thickness difference cannot be recognized by eye-sight, risk ofdefective occurrence due to mixing parts is also minimized.

What is claimed is:
 1. A silent chain, comprising: a first link row thatessentially consists of one guide plate and N pieces of link plates; asecond link row that essentially consists of one guide plate and Npieces of link plates; and a connection pin, wherein the guide plates ofthe first link row and the second link row are in the same shape andsize, the link plates of the first link row and the second link row arein the same shape and size, a plurality of said first link row and saidsecond link row are arranged in a stagger state in a chain longitudinaldirection and connected alternately with the connection pin, and theguide plates and the link plates of the first link row and the secondlink row are composed relatively rotatable to the connection pins.